Concrete Surface Profile (CSP): What the Numbers Mean

Concrete Surface Profile, usually shortened to CSP, is a visual and tactile reference for the texture left on concrete after preparation. ICRI’s CSP system runs from CSP 1 through CSP 10, with the surface becoming progressively rougher as the number increases.

The numbers are not a universal coating-quality score. CSP 3 is not automatically “better” than CSP 2, and CSP 7 is not seven times stronger. The purpose is to describe and verify a surface that fits the thickness and requirements of one selected system.

What the CSP reference system does

ICRI developed molded reference chips so a specifier, installer, inspector, and owner can compare prepared concrete against a common visual standard. The chips represent characteristic textures rather than measuring strength, cleanliness, porosity, or moisture.

A CSP requirement helps answer a narrow but important question: how rough should the concrete be after preparation? It does not answer:

• Whether oil, silicone, sealer, or curing compound remains
• Whether the surface concrete is sound
• Whether moisture is within the coating’s limit
• Whether cracks and joints are treated correctly
• Whether dust has been removed
• Whether the air and slab conditions allow application

CSP is one acceptance criterion inside a larger preparation plan.

How to read CSP 1 through CSP 10

The scale begins with very light texture and progresses to aggressive profiles with exposed aggregate and substantial relief. Low numbers are associated with light surface change. Middle numbers represent increasingly open, textured concrete used under many coatings and overlays. The highest numbers are more typical of thick repair materials and deep overlays than thin resin finishes.

Do not select a number from a generic chart without checking the coating manufacturer’s data. Different products fill texture differently. A low-viscosity primer and a thin clear coat can reveal or fail to cover a profile that a mortar or heavy overlay can accommodate.

System thickness and profile must work together

A thin film placed over a rough profile can leave high points uncovered, trap air, consume unexpected material, and create an uneven finish. A thick system placed over a surface that is too smooth may not develop the mechanical bond intended by its specification.

The goal is balance:

• Thin coatings and sealers generally need a lighter, uniform profile compatible with their ability to wet and cover the surface.
• High-build coatings and broadcast systems can accommodate more texture and may require a more open profile.
• Slurries, mortars, and heavy overlays commonly require progressively more aggressive preparation.

Those are categories, not acceptance numbers. The exact product data sheet or written manufacturer guidance controls.

Preparation methods do not produce one guaranteed CSP

Charts often associate methods with a range of possible profiles, but the equipment name does not guarantee the result. Diamond grinding concrete, shot blasting, scarifying, milling, and abrasive blasting can each produce different textures depending on tooling, machine settings, operator technique, slab hardness, passes, and existing material.

A grinder can polish hard concrete if the tooling stops cutting. A shot blaster can leave stripes if travel speed and blast pattern are inconsistent. A scarifier can fracture or loosen surface concrete if used too aggressively. Specify the result, then adjust the method to reach it.

How CSP should be verified

After preparation and cleaning, compare representative areas directly with the physical ICRI CSP chips under good lighting. Check the open field, edges, corners, patches, low spots, and areas where old coating or sealer was removed.

Photography can document the work, but a photo alone is unreliable because distance, angle, light, wetness, and camera processing change apparent texture. The physical comparison should be made at the slab.

When the project has higher consequences, the specification may also require pull-off adhesion testing, mockups, or other acceptance tests. CSP comparison does not measure tensile strength or confirm that a repaired layer is bonded.

Cleanliness and profile are separate

A rough floor can still be dirty. Preparation exposes pores and creates valleys where fine dust collects. After mechanical work, vacuum the field, edges, joints, cracks, and penetrations with suitable equipment. Do not leave abrasive, powder, or loose concrete for the primer to bind.

Contaminants should be addressed before profiling when possible. Grinding over oil can spread it. Texturing a sealer without fully removing it can leave islands of bond-inhibiting material. A preliminary absorbency check, test area, or additional removal may be necessary.

Moisture is not visible in the CSP number

Opening the surface can change how quickly water at the top evaporates, but it does not tell you the condition deeper in the slab or below it. Use the selected quantitative method and compare results with the proposed system. The guide to moisture testing concrete before epoxy explains the difference between screening and acceptance testing.

A floor can meet the required profile and still develop bubbles or blisters in epoxy from outgassing, condensation, vapor, mixing, or application conditions. Profile is important, but it is not a diagnosis for every defect.

Common CSP mistakes

• Specifying a method instead of a result: “Grind the floor” does not define the profile.
• Assuming rougher is safer: Excessive texture can exceed the coating’s cover capacity.
• Checking only the open field: Edges and low areas may remain sealed or smooth.
• Comparing before final cleaning: Dust can hide the real surface and alter its feel.
• Using an online image as the standard: Physical CSP chips are the reference.
• Ignoring surface strength: The right texture in weak concrete is still weak.

What to put in a proposal or specification

A useful preparation section should identify:

• The target CSP or manufacturer-required profile
• Materials and contaminants to be removed
• Permitted preparation methods
• Edge, corner, joint, and penetration requirements
• Dust-control and final-cleaning requirements
• How the profile will be verified
• Additional strength, moisture, or adhesion tests

If the coating manufacturer changes, the profile requirement may also change. Confirm the target against the final approved system before mobilization.

Acid etching and CSP

Chemical etching can change a concrete surface, but the outcome depends on paste, finish, porosity, contamination, reaction, rinsing, and drying. It is difficult to use that process to remove coatings or verify a consistent mechanical profile across a mixed slab. Read acid etching vs. grinding concrete before treating “etched” as a CSP acceptance result.

The bottom line

ICRI CSP numbers give the project team a shared language for surface texture. They do not replace the product data sheet, physical reference chips, or the other tests that establish cleanliness, soundness, moisture, and environmental readiness.

Louisville Coating Company matches preparation to the specified epoxy floor coating, then verifies the surface left behind. The correct CSP is the one the complete system is designed to cover and bond to.